The combined refrigerators with forced air circulation are provided with ducts for the conduction of cold air coming from the evaporator, to both the freezing and the refrigerating compartments.
In a prior art construction, the ducts, which promote the fluid communication of the freezing and refrigerating compartments with the evaporator, are constructed in EPS molded pieces, normally three pieces, comprising a base, a cover, and a complement, defining a hollow block, which is mounted to the inside of the intermediate wall of the freezing and refrigerating compartments, before the cabinet walls are filled with a thermal insulation material.
In another construction pertaining to the state of art, the air ducts, which promote the fluid communication of the freezing and refrigerating compartments, are formed in plastic pieces, which are normally blow molded, and whose ends are connected to specific points of the compartments. These pieces are externally covered with the thermal insulation material, which is subsequently injected to the inside of the cabinet walls.
In both prior art constructions considered above, the captation of cold air from the evaporator, to be supplied into the refrigerating compartment, is laterally made through an air distribution plenum provided in the rear region of the freezing compartment, since the fan that impels the airflow is centrally positioned in the cabinet. The need of providing the captation of cold air to the refrigerating compartment in an offset position in relation to the central plane of the cabinet is due to the presence of an air return duct that is centrally provided through the intermediate wall, from the front upper region of the refrigerating compartment to the lower region of the evaporator. Thus, for providing the downward directioning of the refrigerated airflow from the evaporator to the rear upper region of the refrigerating compartment, it is necessary to provide a “curved” path, laterally surrounding the air return duct of the refrigerating compartment, in order to have an outlet end inferiorly positioned in relation to said return duct and in communication with a descending central rear duct for supplying refrigerated air to the refrigerating compartment.
There is also the prior art solution designed to be applied to a basic combined refrigerator, of lower cost and in which the distribution of forced airflow is made through a central rear tower in the freezing compartment, and having the return of air by the lower part of the evaporator in the freezing compartment itself and in the rear upper region of the refrigerating compartment. In this type of construction, the captation of air from the refrigerating compartment to the evaporator is effected directly below the evaporator, no interference occurring between the refrigerated air duct coming down from the evaporator to the refrigerating compartment and the air return duct that is centrally mounted in the interior of the intermediate wall. However, this solution presents some disadvantages related to the construction and to the layout of the ducts inside both compartments, as well as to efficiency losses in terms of air circulation.